In U.S. Pat. No. 3,860,270 there is disclosed a coupling comprising a sleeve for fitting over the end of a pipe. The sleeve has means for sealing the sleeve against the pipe and means for gripping the pipe. The sealing means comprises an annular groove containing a sealing member and a chamber which communicates with the exterior and can be filled with a hardenable composition and maintained under pressure until set to force the sealing member into sealing contact against the outer surface of the pipe. The gripping means comprises annular grooves on the inside of the sleeve which accommodate jaw sectors with gripping teeth, sealing members in the grooves behind the jaw sectors and a chamber which communicates with the exterior and can be filled with a hardenable composition and maintained under pressure until set to cause the gripping teeth of the jaw sectors to bite into the outer surface of the pipe.
The sealing member of the sealing means comprises a sealing ring which forms a seal against the sides of the annular groove and against the pipe and the chamber is formed by the space in the groove behind the sealing ring. Similarly the sealing members of the gripping means comprise sealing rings which form seals against the sides of the annular grooves and the pressure chambers are the spaces in the grooves behind the sealing rings.
The arrangement of U.S. Pat. No. 3,860,270 is considered to be unsatisfactory in that the sealing rings do not provide satisfactory seals for use at high pressures.
It is the object of the present invention to provide a pipe coupling which overcomes the aforementioned disadvantage.